This is a pack of ten ProTek R/C 3x5x0.5mm Clutch Washers. These washers have a 3mm inner diameter, with a 5mm outer diameter and are 0.5mm thick. These can be used in a variety of applications, but are intended to be installed between an aluminum clutch shoe and the flywheel, and used as clutch shoe shims on any clutch that uses a 3mm pin.